Streamlining bit assemblies for road milling, mining and trenching equipment

ABSTRACT

An improved bit assembly for road milling, mining, and trenching equipment includes a streamlined tip assembly that is a combination of conical and cylindrical in shape and devoid of protrusions or annular indentations that might impede the flow of removed material over and around the bit assembly or provide space for removed material to become clogged or imbedded on the tip assembly. The portion of the bit block which mounts on a drum or endless chain extends from a cylindrical portion of the bit block and provides opposed angled shoulders which extend downwardly and away from a central ridge on the bit block to again provide for efficient flow of removed material over and around the bit block. As a part of the improved bit assembly, several embodiments of improved bit holders are disclosed including one embodiment having a notch along the back side of the bit holder tip portion for allowing the insertion of a tool therein to aid in removal of the bit holder from the bit block, and a second embodiment wherein the shank of the bit holder includes a pair of opposed elongate slots therethrough that provide a resilient middle section of the bit holder shank to aid in providing an increased interference fit for that shank in the bit holder. Also, an improved tool is disclosed that is insertable in a bit holder to allow the bit holder to be removed from the bit block by applying force to the front of the bit holder as mounted in the block.

[0001] This invention relates generally to road surface removal orreclaimer-stabilizer equipment and mining equipment and moreparticularly to bit assemblies including bits, bit holders and bitblocks that are more efficient in their cutting and passage of the cutmaterial around the bit assembly. This is a continuation-in-part of Ser.No. 09/500,983 filed Feb. 15, 2000.

BACKGROUND OF THE INVENTION

[0002] Bit assemblies are utilized in road, off-road and miningmachinery on the perimeter and across the width of a rotary drum or onthe outside of a continuous chain or the like where the bits are movedthrough an orbit which is intercepted by the face of the material beingremoved or recycled. Road milling equipment removes the defectivesurface of a road and smoothes the top of all or selected portions ofthe road surface. The bits utilized include a tip and a shank. The shankis received and may axially rotate in a bit holder which is secured ontoa bit block that, in turn, is mounted on the drum. Each of the bits hasa hardened tip, preferably made of tungsten carbide or such otherhardened material that acts to remove a portion of the surface itcontacts. By using a sufficient number of these bits around the outersurface of a rotating drum, a large amount of surface may be worked.

[0003] The bit assembly including the bit, bit holder and bit block, acton the portion of the surface it is removing to separate that surfacefrom the underlayment and as the drum rotates, passed that surface overthe outside of the bit assembly. The milling of concrete and macadamsurfaces required a substantial power output to operate the drum orcontinuous chain or the like. With the use of such a substantial poweroutput to operate the heavy milling machinery, a need has developed toprovide a more efficient bit assembly that utilizes less power toperform the same function as machines fitted with prior art bitassemblies.

[0004] In O'Neill et al, U.S. Pat. No. 4,915,455, a substantiallyfrustoconical bit is mounted upon a block that provides a large mostlyflat forward leading surface that impedes the flow of macadam orconcrete therearound and provides a barrier to movement of the bit onadditional portions of the surface to be milled.

[0005] Additionally, a need has developed for providing ease ofremovability of bit holders in their bit blocks, especially whenportions of or all of the assembly becomes worn and in need ofreplacement. U.S. Pat. No. 5,374,111 discloses an undercut flange at thebottom of a base of a bit that allows a pry bar to be wedged betweenthat flange and the top of the bit block to help remove a bit from thebit block. It would be desirable to provide more efficient means andmultiple means for allowing the removal of a bit holder from a bitblock. Additionally, heretofore known bit holders have been retained inbit blocks by the use of threaded nuts or retainer rings. A need hasdeveloped to provide means to mount the shank portion of a bit holder ina bit block without the need of a fastener on the distal end of the bitholder shank to retain same in the bit block.

[0006] Further, a need has developed for a truly quick-change type ofbit holder that may easily and quickly be inserted in the bit block andremoved therefrom.

[0007] It is, therefore, an object of the present invention, generallystated, to provide an improved means for quickly mounting and/orremoving a bit holder from its associated bit block.

[0008] Another object of the present invention is the provision of amore efficient bit assembly that requires less power to run when mountedon road milling equipment than heretofore known bit assemblies whileproviding longer lasting useful life of operation.

[0009] A further object of the present invention is the provision ofmultiple means for retaining a bit holder in a bit block by means of aresilient interference fit between the holder and the block.

[0010] Another object of the present invention is the provision of aneasily mounted tool on the bit holder that facilitates the removal ofthe bit holder from the bit block at the front of the leading surface ofthe bit holder without the need for a large amount of access to the rearof the bit block.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The features of the present invention which are believed to benovel are set forth with particularity in the attached claims. Theinvention may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings in whichlike numerals refer to like parts and in which:

[0012]FIG. 1 is a side elevational exploded view of a bit assemblyconstructed in accordance with the present invention;

[0013]FIG. 2 is a fragmentary cross-sectional view with certainmodifications taken substantially along line 2-2 of FIG. 1 with theitems of FIG. 1 shown in mounted position on each other;

[0014]FIG. 3 is a bottom ¾ perspective view of a second embodiment ofthe invention showing a bit holder mounted in a bit block;

[0015]FIG. 4 is a top ¾ end perspective view of the second embodiment ofthe present invention;

[0016]FIG. 5 is a front ¾ perspective view of the second embodiment ofthe present invention;

[0017]FIG. 6 is an upper side perspective view of the second embodimentof the present invention;

[0018]FIG. 7 is a top plan view of a third embodiment of a bit holder ofthe present invention;

[0019]FIG. 8 is a side elevational view of the third embodiment bitholder of the present invention;

[0020]FIG. 9 is a front end elevational view of the third embodiment ofthe bit holder of the present invention;

[0021]FIG. 10 is a top plan view of a fourth embodiment of a bit holderof the present invention;

[0022]FIG. 11 is a front end elevational view of the fourth embodimentof a bit holder of the present invention;

[0023]FIG. 12 is a side elevational view of a tool to facilitate removalof a bit holder from a bit block;

[0024]FIG. 13 is a cross-sectional view similar to FIG. 2 showing asecond embodiment of the plunger of FIG. 1.

[0025] Referring to FIG. 1, a bit, bit holder and bit block assembly,generally indicated at 15, constructed in accordance with the presentinvention, includes a bit, generally indicated at 16 and a spacer,generally indicated at 17, together with a bit holder, generallyindicated at 18 and a bit block, generally indicated at 20.

[0026] The bit 16 includes a hardened tip 21, usually made of tungstencarbide. The base of tungsten carbide tip 21 (not shown) resides in apocket (not shown) in the front face 22 of a frustoconical forwardportion 23 of bit 16. At the rear of the frustoconical portion 23 is acylindrical front portion base 24. In this embodiment, the cylindricalbase 24 performs a function which is analogous to prior art known as a“tire portion” of the bit because in that prior art the outside of thebase portion has a rounded shape similar to the outside of a donut ortire. Aft of the cylindrical base 24, the tip narrows to a cylindricalshank 25, which, in this embodiment, includes a C-shaped retainer 26therearound and a cylindrical shank portion base 27 defining the rearend of the bit.

[0027] The spacer 17 is shaped similarly to the shank portion 25-27 ofbit 16 in that it includes opposed cylindrical ends 28, 30 and aslightly narrowed cylindrical shank portion 31 mounted therebetweenhaving a C-shaped retainer 32 positioned therearound. At the outside ofthe opposed cylindrical end 30 is a spherical indent 33 whose purposewill be discussed in more detail below.

[0028] In this embodiment of the present invention, the bit holder,generally indicated at 18, is termed a bulbous shaped bit holder as thefront generally conical portion includes a middle section having aconvex outline. The leading portion of the generally conical frontsection of bit holder 18 includes a cylindrical nose 34, having a flatannular face 35 from which a central bore 36 extends axially all the waythrough the bit holder. A plurality of notches 37-37 (one shown)adjacent the front face 35 of the bit holder, provide an access area tothe cylindrical base 24 of the tip 16 into which a prying tool may bepositioned to force out the base 24 of the bit 16 when the bit shank 25and spacer 17 are mounted in the bore 36 of the bit holder 18.Rearwardly adjacent the nose 34 is the bulbous portion 38 of thegenerally frustoconical front section of the bit holder 18. Rearwardlyof the bulbous section 38 is the cylindrical base 40 which performs asimilar function in the bit holder 18 that the cylindrical base 24performs in the bit 16.

[0029] Aft of the base 40 of the conical front portion of bit holder 18is the shank 41. The shank portion 41 includes an upper shoulder 42which is slightly larger diameter than the middle shank portion 41, anda second enlarged portion 42 of shank 41 immediately adjacent the distalend 43 thereof. A slot, whose forward end is indicated at 44 extendsfrom the end of upper shoulder portion 32 through the distal end 43 ofthe shank 41 thus providing a C-shape for the perimeter of the shank 41allowing it to expand and contract diametrically for a force fit intothe bit block, generally indicated at 20. A pin 45 is mounted in a bore46 180 degrees around shank 41 from the slot 44. The pin 45 assures thatthe spacer 17 will not fall out of the bottom of bit holder bore 36 inthe bit holder 18 when it is mounted therein.

[0030] In another important aspect of the present invention, the bitblock 20 includes a base mounting portion 47 having a base 48 which ismountable on the outside of a drum (not shown) which is a part of roadmilling equipment. The front or leading portion of the mounting section47 includes a pair of rearwardly angled shoulders 50-50 (only oneshown). Adjacent the mounting section 47 which holds the bit block onthe drum is a generally annular cylindrical bit holder mounting portion51 having a central bore 52 positioned therethrough from a top surface53 to a bottom distal portion 54 of the bit block 20. Adjacent thebottom portion 54 and opposite the mounting portion 47 is a slot 55which increases the accessibility of a tool to the rear of the bit blockand into the bore 52 of the bit block 20 at the rear 54 thereof. Also,immediately above slot 55 is a cylindrical bore 56 which may have a pin(shown in FIG. 3 and 5 at 56 a). Pin 56 extends into the slot 44 of thebit holder, thus preventing rotation of same when mounted in the bitblock. As is evident from the exploded view, the shank portion 41 of thebit holder 18 is press fit into the bore 52 of the bit block 20 andretained therein. Further, the spacer 17 and the shank portion 25 of bit16 are mountable through the front end 35 of the bit holder 18 and areretained therein by C-shaped retainers 26 and 32. Additionally, thespacer is retained in its mounted position by pin 45.

[0031] Referring to FIG. 2, the mounting relation between the bit block20, bit holder 18, spacer 19 and bit 16 is shown in cross section. FIG.2 is modified from a straight cross section of the assembly as shown inFIG. 1 in that the slot 44 of bit holder 18 and the slot 55 of bit block20 are not seen so that the mounting relation between the bit block andbit holder may be shown in more detail. Additionally, the upper shoulder42 of the bit holder is not shown so that the relationship between thelower shoulder 42 a and the bit block bore 52 may be shown.

[0032] As is shown most clearly in FIG. 2, the lower raised shoulder 42a of the shank portion 41 of the bit holder 18 is press fit into thebore 52 of bit block 20. The press fit between the two is on the orderof four times the ordinary press fit between a cylindrical male memberand an annular bore because the C-shape cross section of the shank isresilient with the addition of slot 44 therein. This allows the lowershoulder 42 a to be positioned in bore 52 with such a substantial pressfit that neither a retaining nut nor retaining ring is necessary tomaintain the bit holder in the bit block. However, because of vibrationand potential rotation of the bit holder in the bit block, a pin 56 a(FIG. 5) is mounted through bore 56 into the slot 44 (FIG. 1) of the bitholder shank in order to maintain the bit holder and bit block incorrect non-rotating mounted orientation. As additionally shown in FIG.2, the bit 16 and spacer 17 are mounted in the central bore 36 of bitholder 18 and retained therein by C-shaped retainer clips 26 and 32. Asshown most clearly in FIG. 2, the semi-cylindrical indent 33 in thespacer 17 provides for the insertion of a tool through the backside ofbore 36 which will accommodate punching out the spacer 17 and the bit 16from the back of the assembly.

[0033] As also shown most clearly in FIG. 2, in an important aspect ofthe present invention, the profile of the bit, bit holder and bit blockmaintains either a cylindrical outline or a conical outline although theconical outline may be slightly concave or convex also, to provide asmooth efficient aerodynamic outer surface which in this case does nothave air passing by it, but has macadam or concrete passing by it. Thissmooth outer surface of the bit 16, bit holder 18 and bit block 20 alsobenefits from the opposed shoulders 50 at the leading surface of the bitblock 20. The aim in providing this efficient aerodynamic profile is toboth provide longer life for the assembly and the portions thereof, andto provide for more efficient separation of the macadam or concrete andpassage of same by the assembly, thus requiring less power to run theroad milling equipment and also providing longer life for the assembly15 when performing its function. Generally, the lack of sharp edges andthe lack of cylindrical outcroppings along the surface, or indents alongthe surface, provide fewer areas for macadam or concrete to sharplyimpact the surface or become imbedded thereon, thus assuring a moreefficient and longer work life for the assembly 15 and the partsthereof.

[0034] In operation, prior art road milling bit, bit holder and bitblock assemblies normally operate for between three and four hundredhours before the parts wear out or a failure occurs in at least one partof the assembly. Applicant's bit, bit holder and bit block assembly havebeen operated for more than 1000 hours without serious deterioration ofthe assembly or failure of parts thereof. Also, the use of the assembly15 of the present invention on road milling equipment has provided amilling system which consumes less gasoline per hour to operate. Whilegas consumption of the road milling equipment varies depending on depthof cut, temperature, surface to be milled, etc., over a long period oftime, it is believed that the bit assembly of the invention yields abouta 10 percent improvement over prior art bit assemblies.

[0035] Referring to FIGS. 3-6, a second embodiment of the presentinvention is shown utilizing the bit block 20 of the first embodimenttogether with a concave style bit holder, generally indicated at 60. Bitholder 60 differs from bit holder 18 not only in that it is concave inits conical leading portion, but also because it has a hardened annularinsert 61 preferably made of tungsten carbide positioned at its leadingsurface. Since the hardened insert 61 extends towards the outside of theconcave, but generally conical forward surface 62 of the front portionof bit holder 60 to provide structural strength, there are no notches inthe concave surface 62. With this embodiment, the bit 16 (not shown)would be driven out of the bit holder 60 for replacement by inserting arod to tool (not shown) in the bottom of bore 63 of the bit holder(shown most clearly in FIG. 3) until it is stopped by semi-sphericalindent 33 of spacer 17 (FIG. 2) where a hammer struck on the end of thetool will drive the bit 16 outwardly of the bit holder 60. The use of ahardened insert 61 has been shown to increase the work life of the bitholder 60 by providing a tougher mounting for the bit 16 in the bitholder 60.

[0036]FIGS. 4 and 6 tend to show the increased efficiency obtained byutilizing opposed shoulders 50-50 to direct macadam away from theforward portion 50 a and third shoulder 50 b of the bit block mountingportion. Also, as mentioned previously, and shown in FIGS. 3 and 5, thepin 56 a is aligned with the slot 64 in the shank of bit holder 60 toprevent rotation of the bit holder 60 in the bit block 20 when mountedtherein. Additionally, FIG. 3 shows the accessibility of the shank 65 onbit holder 60 through the rear 54 of the bit block 20. Shown mostclearly in FIGS. 3-6, the forward facing surfaces of the bit holder 60and bit block 20, with the exception of leading surface 50 a forstrength of part reasons, all extend rearwardly and outwardly to providea smooth, efficient deflecting surface for material separated from themacadam or concrete by the bit 16.

[0037] Referring to FIGS. 7, 8 and 9, a third embodiment of a bit holderis shown generally at 70. Bit holder 70 is similar to the bit holder 18in that it is a steel front bulbous type having a slotted shank. Thesteel cylindrical flange front 71 includes an annular steel face 72similar to the first embodiment. The bulbous frustoconical portion 73extends rearwardly beyond the cylindrical nose and includes a pair ofnotches 74, 75 therein that provide tool access to the back of a bit foreasing removal of the bit from the bit holder.

[0038] At the rear of the bulbous frustoconical portion 73 is thecylindrical base 75. In one important aspect of the present invention,the base 76 includes a rectangular notch 77 that extends radiallyinwardly from the outside of the circumference of cylindrical base 76and is also in communication with the back face 76a of the cylindricalbase. When the bit holder 70 is mounted in the bit block, such as 20,notch 77 will allow access of a tool therein to provide a prying methodfor removing the bit holder from the bit block. This is especiallyimportant if, for some reason, access to the back of the bit holder isnot obtainable. A prying tool positioned in notch 77 would provide forremoval of the bit holder out of the bit block until after the uppershoulder 78 of shank portion 79 is free of the top of the bit block,thus easing removal of the bit holder from the bit block.

[0039] Referring to FIGS. 10 and 11, a fourth embodiment of the bitholder of the present invention, generally indicated at 80 is a steelnosed bit holder similar to that shown in FIG. 1, i.e., a bulbous stylefrustoconical nose bit holder, with the exception that the notches 82,83 are round in outline rather than rectangular as shown in the firstembodiment 18. The frustoconical portion at the front of the bit holder80 includes the cylindrical nose 84, bulbous frustoconical portion 85and cylindrical base 86. Rearwardly of the base, the shank portion 87includes an upper shoulder 88 similar to that shown in the firstembodiment. However, the remainder of shank 87 differs from the shank 41of the first embodiment in two ways. First, instead of having a slotextending from the edge of upper shoulder 88 to the distal end 89 of theshank, the fourth embodiment of the present invention includes a pair ofdiametrically opposed slots 90 from the upper shoulder 88 to the forwardedge of the distal end 89 such that the distal end 89 is still annularin shape rather than C-shaped as in the first embodiment 18. The seconddifference in the shank portion between the first embodiment and thefourth embodiment, is that the lower shoulder portion 91 is movedforwardly on the shank to be at a position to bisect the opposed slots90. In this embodiment, the pair of opposed slots take away stiffnessfrom the annular shank such that the lower shoulder portions 91 areresilient similar to the lower shoulder portion 42 a of the firstembodiment even though the distal end 89 of the shank is continuouslycircular or annular in shape. The press fit of the lower shoulder 91 inthe bore 52 of the bit block 20 is similar to that of the lower shoulder42 a of the bit holder 18 in that it is a greater interference fit thanthat found in typical male-female member press fits, thus providing forease of secure mountability of the bit holder 80 in the bore 52 of bitblock 20. As with the other embodiments, no nut or retainer is necessaryto hold the bit holder in the bit block. Also, pin 56 a fits in eitherof the slots 90-90.

[0040] Referring to FIG. 12, a tool for aiding removal of the bit holder18 from the bit block 20 is generally indicated at 90. Tool 90 includesan elongate bolt 91 having a hex head 92, a shank 93 that extendsthrough the bore 36 of the bit holder 18 and out the distal end 43thereof where a hex head nut 94 may be turned on the threads 95 at thedistal end of the shank portion 93 of bolt 91. An enlarged radiallyextending flange 96 has a central bore 97 through which the bolt shank93 is passed prior to inserting the bolt through the bit holder bore 36.The large flat surface 96 a on the rearward side of annular flange 96provides ample room for positioning the tool thereagainst or striking ahammer thereto to remove the bit holder 18 from the bit block 20 withoutneeding a large amount of access to the rear of the bit block 20 otherthan room to fit nut 99.

[0041] Referring to FIG. 13, a second embodiment of spacer or plunger,generally indicated at 105, performs the same function as spacer 17, iscylindrical in outline and slidingly fits in the central bore 106 of bitholder 107. Spacer of plunger 105 includes an elongate infernal slot 108extending mediate the front end 110 and rear cupped end 111 thereof. Aperpendicular bore 112 radially through the shank sidewall 113 secures apin 114 that extends into slot 108 to limit the movement of the spacerin the bore. An additional notch 115 in spacer 105 provides for removingthe spacer from the bit holder 107 by driving the pin into the notch.Unlike spacer 17, spacer 105 does not need a retainer 32 to keep itmounted in its respective bit holder bore. Thus, an improved roadmilling bit assembly spacer, bit holder and bit block have been shownand described together with three additional embodiments of the bitholder and a bit holder removing tool. The bit assembly in beingefficiently smooth and lacking in substantial annular discontinuitiesaround the bit provides an efficiency of use when the bit separateseither macadam or concrete and also provides for an efficient passage ofsuch material around the bit assembly that lessens wear on the assemblyand requires less power to drive the assembly through the macadam orconcrete while also providing greater bit assembly life and requiringless fuel per hour to drive the assembly than heretofore known bitassemblies.

[0042] While five differing embodiments of the present invention havebeen shown and described, it will be apparent to those skilled in theart that many changes and modifications may be made without departingfrom the true spirit-and scope of the present invention. It is theintent of the appended claims to cover all such changes andmodifications which fall within the true spirit and scope of theinvention.

What is claimed:
 1. A bit holder for use in road milling, trenching andmining equipment as part of an assembly including a bit, bit holder andbit block, said bit being mountable in a first bore through said bitholder and said bit holder being mountable in a second bore through saidbit block, said bit holder comprising: a bit receiving front portionterminating at an annular flange for engaging a face of said bit blockand a shank portion extending axially rearwardly from said annularflange, said bit receiving front portion including a front annular faceincluding a first bore extending centrally axially therefrom throughsaid bit holder, and outer circumference of said front annular facebeing substantially identical to a widest outer circumference on saidbit, said bit receiving front portion further including a generallyfrustoconical surface extending axially from said front annular facetoward said annular flange until an outer diameter of said generallyfrustoconical surface substantially equals an outer diameter of saidannular flange, and a cylindrical surface extending axially from saidgenerally frustoconical portion to said annular flange, said bitreceiving front portion between said front annular face and said annularflange being devoid of any surface extending axially toward said annularflange and radially inwardly from an outer surface thereof.
 2. The bitholder as defined in claim 1 wherein an axial line segment along saidgenerally frustoconical surface is convex in shape.
 3. The bit holder asdefined in claim 1 wherein an axial line segment along said generallyfrustoconical surface is concave in shape.
 4. In combination, a bitholder and a bit block mountable on one of a drum and continuous chainfor use in road milling, trenching and mining equipment, saidcombination comprising: a bit holder having a generally frustoconicalfront portion and a shank rear portion, said generally frustoconicalfront portion including a flat annular nose surface having an axiallyextending central bore in communication therewith, a frustoconicalsegment and a cylindrical base, said shank portion extending axiallyfrom said cylindrical base, a bit block including a drum mountingportion and a bit holder mounting portion, said drum mounting portionincluding a drum mounting surface and a leading forward surfaceextending at an acute angle from said drum mounting surface, saidleading forward surface including an elongate leading ridge and opposedsloping shoulders extending downwardly and outwardly from said leadingridge for efficiently aiding the flow of removed material over andaround said bit block drum mounting portion, said bit holder mountingportion extending from said drum mounting portion being generallycylindrical and including a central bore generally perpendicular to saidleading ridge for mounting said bit holder therein, a diameter of saidgenerally cylindrical bit holder mounting portion being substantiallyidentical to a diameter of said bit holder cylindrical base forefficient movement of removed material therearound.
 5. The combinationas defined in claim 4 wherein a downwardly and circumferentiallyextended edge of each of said opposed shoulders defines a juncturebetween said drum mounting portion and said generally cylindrical bitholder mounting portion.
 6. The combination as defined in claim 5wherein said outer generally cylindrical surface of said bit holdermounting portion, with the exception of said juncture with said drummounting portion, is devoid of any protrusions that would impede theflow of removed material thereover.
 7. The combination as defined inclaim 4 wherein said opposed sloping shoulders extend partwaycircumferentially around said generally cylindrical bit holder mountingportion for deflecting removed material away from a juncture of saiddrum mounting portion and said bit holder mounting portion.
 8. A bitholder for use in road milling, trenching and mining equipment as partof an assembly including a bit, bit holder and bit block, said bit beingmountable in a first bore through said bit holder and said bit holderbeing mountable in a second bore through said bit block, said bit holdercomprising: a bit receiving front portion terminating at an annularflange for engaging a face of said bit block, a shank portion extendingaxially rearwardly from said annular flange, said shank portionincluding a declining taper from adjacent said annular flange toadjacent a distal end thereof, said declining taper providing aninterference fit between said bit holder and said bit block, a pair ofradial slots each through one half of said shank portion perpendicularto an axis of said first bore from said outer surface of said decliningtaper to said axial bore centrally therethrough, said slot extendingaxially from a position axially inwardly adjacent said distal end ofsaid shank terminating at a predetermined axial distance from saidannular flange for providing increased resilience for an outer surfaceof said declining taper to increase the usable interference fit betweensaid declining taper and said second bore on said bit block by at leastabout four times a standard interference fit therebetween.
 9. The bitholder as defined in claim 8 wherein a pair of radial lands defined asbeing between said pair of radial slots are sized to provide saidinterference fit with said bit block bore prior to inserting said shankin said bit block bore.
 10. The bit holder as defined in claim 8 whereina pair of radial land between said pair of radial slots provide aresilient interference fit with said bit block bore while a distal endof said shank maintains its predetermined annular dimensions.
 11. In abit assembly for use in road milling equipment of the type including abit, a bit holder including a first central bore in which a shank ofsaid bit is mounted, and a bit block including a second bore in whichsaid bit holder is mounted, an improvement comprising: a cylindricalspacer shaped substantially identical to a shape of said shank on saidbit, said cylindrical spacer being mountable in said first central borebetween a distal end of said bit shank and a bottom end of said bitholder, a bottom of said cylindrical spacer providing means forreceiving a bit removing tool thereon in close approximation to saidbottom of said bit holder for aiding in removing said bit from said bitholder.
 12. The bit assembly as defined in claim 11 wherein said bitholder includes means in communication with said first central bore forpreventing said cylindrical spacer from exiting said first central boreout said bottom of said bit holder.
 13. The bit assembly as defined inclaim 12 wherein said means for preventing said cylindrical spacer fromexiting said first central bore out said bottom of said bit holdercomprises: an elongate axially oriented slot in communication with acylindrical sidewall of said cylindrical spacer positioned mediate a topand said bottom thereof, a radially extending bore through an annularsidewall of said shank on said bit holder, and a cylindrical pin mountedon said radially extending bore and extending into said elongate axiallyoriented slot on said cylindrical spacer for limiting the slidingmovement of said cylindrical spacer in said bit holder central bore. 14.The bit assembly in claim 13 wherein said elongate axially oriented slotincludes at least a portion thereof having a depth greater than a lengthof said cylindrical pin for accepting said pin when it is desired toremove said cylindrical spacer from said bit holder central bore.
 15. Abit holder tool for use in removing a bit holder from a bit block bore,said tool comprising: a shank portion defining an elongate rod beinglonger than said bit holder having an enlarged head end and a fastenerreceiving a distal end, a fastener engageable on said distal endadjacent a bottom of said bit holder, and a circular disk having a borecentrally therethrough for mounting said shank portion therethrough,said circular disk having a diameter larger than the diameter of saidbit holder for providing a surface for impingement of a hammer or chiselthereon to provide an axial force component to said elongate rod toforce said bit holder from said bit block.